Scientific Importance
by sublime42
Summary: Tony decides that he needs to test the limits of Steve's metabolism for scientific purposes (okay, not really, it's a thing for him). Steve is a bit unsure about the whole thing but eventually bends to Tony's will and allows himself to be stuffed by the genius.


**A/N: Filled this prompt:**

**Tony decides that he needs to test the limits of Steve's metabolism for scientific purposes (okay, not really, it's a thing for him). Steve is a bit unsure about the whole thing but eventually bends to Tony's will and allows himself to be stuffed by the genius. The serum can only withstand so much before the food causes Steve's gut to round out and sit nice and plump in his lap and Steve finds that he's actually quite turned on by it. Tony is thrilled with the results. Sexy time can occur if you want but it isn't really necessary.**

00

"Come on, it's not that big of a deal! Your body will totally work it out."

Steve sighed.

"I just don't see the point in it."

Tony grinned.

"It's for science! Don't you want to support my research? It'll be interesting information for you, too."

Steve rolled his eyes. Tony had been trying to convince him to participate in his "experiment" for weeks. The idea was to see how much food Steve could consume before he felt some physical repercussion from it.

Tony had noticed that, due to Steve's heightened metabolism, he was frequently hungry. He could eat a lot, too, but it never seemed to show, as in, Steve never seemed to feel full. He never looked full, either. Tony had never seen him rest his hand on his stomach after eating a large meal, nor had he ever even seen Steve's stomach distended in any way.

And Tony would've noticed that, too. He had a kink for that type of thing, and he would have liked nothing more than to see his lover stuffed so much that he could barely move. Still, he wasn't sure if Steve would really be into it so using the guise of "an experiment of scientific importance" seemed to be his best bet.

"I don't know," Steve replied, "I mean. I guess, if you really think it's that important."

"Really?!" Tony realized how excited he sounded a second too late. He had to force himself to appear more calm. "I mean, that's great. It'll let us know the correct amount of supplies we should have on hand for you during longer missions."

"Yeah, okay. I guess you'll be getting everything ready?"

"Of course. We can do it tomorrow morning. The team will be gone so there won't be any distractions."

He pulled Steve close and kissed him on the lips. "You're the best. I'm, uh, sure that the information we get from this will be extremely helpful."

Steve smirked and kissed him back, wondering what Tony was really up to.

00

That evening Tony couldn't sleep. Steve had drifted off long ago and was snoring beside him, but all he could think about was the events to come. In mere hours he would be fulfilling his fantasy. He got hard just thinking about it.

Figuring that he wasn't going to get any sleep anyway, Tony decided to get started on some of the shopping and cooking that needed to be done. He fully intended to have enough to fill up their large dining room table. Thankfully, there were a bunch of 24 hour supermarkets nearby. Gotta love New York.

Tony quietly climbed out of bed and got dressed, then made his way out. He didn't care if he would be tired tomorrow. Surely the excitement of what was going on would keep him awake.

00

Steve woke up around 8am. The first thing that he noticed was that Tony wasn't next to him. The second thing he noticed was the smell of something cooking. It almost smelled like pancakes. He was wondering why the heck Tony would be making pancakes when he remembered what was to happen that day.

Today, he'd be participating in Tony's experiment.

Steve stretched then got out of bed. He slipped on the hokey pair of Iron Man branded slippers that Tony had bought him and walked out of the room, then followed the smell of pancakes. Soon enough he found himself in the kitchen.

"Good morning," Steve greeted his boyfriend.

Tony jumped in response and dropped his spatula.

"Oh, fuck," Tony hissed, "Shit. Sorry." He picked the instrument up and ran it under some water in the sink.

"Uh, you okay there?" Steve asked, concerned.

Tony smiled.

"Oh, yes, absolutely fine. Just a little jumpy was all. I've been up for a while. Wait til you see what I've prepared, just after I finish…" Tony pushed the spatula under a pancake then placed it on a plate, "...That. I'm done now."

"O...kay."

Tony looked Steve up and down and noticed that he was wearing his favorite set of blue pajamas. Even though they'd been dating and having sex for months, Steve still insisted on wearing the pajamas to bed while Tony slept naked.

Today, though, they were a good choice.

"It's good that you're wearing those. They'll be the most comfortable."

Steve raised an eyebrow but didn't say anything. Instead he allowed Tony to lead him into the dining room. His jaw dropped when he walked in.

The entire table was covered with various plates of food. There were loaves of bread and a plate of biscuits, a large plate of cinnamon buns, different types of meat, mashed potatoes, a huge salad, various desserts and three boxes of pizza… The list went on.

Steve stared at the table for a second before turning to Tony.

"This is wrong, we should donate this to a homeless shelter or food pantry or something."

Tony reached into his pocket and pulled out a piece of paper. He showed it to Steve.

"Here's the receipt. Notice the statement on the bottom, right there," he pointed to the spot he was talking about.

"Donation of one hundred thousand dollars to the Manhattan Food Pantry," Steve read off.

"Yeah. I figured you'd feel bad so I took all of those little slips they give you at the registers and paid them off." Tony was referring to the food pantry donation cards that grocery stores often kept near their cash registers.

"Wow. You thought of everything."

"Well, being a genius and all… Anyway, don't feel bad, the food pantry will have more than enough money for all it needs, at least for the next few weeks, and a couple of happy cashiers got photos with me so it all worked out.

"It sure seems like it." Steve continued to stare in awe at the amount of food that Tony had prepared.

"So… I don't know about you but I'm ready to start the experiment," Tony said, trying his best not to sound too happy about it.

"Uh, yeah, okay."

Tony took Steve's hand and led him over to a seat at the head of the table.

"You can sit there."

Steve sat down and looked up at Tony, waiting for him to call JARVIS or take out a notepad or do something scientific. Tony seemed to understand this.

"JARVIS, keep track of the amount of calories that Steve eats and their percentages in relation to protein, carbohydrates and fat."

Tony had just made that up off the top of his head, but it seemed to appease Steve.

"Yes, sir," the AI replied.

"Good." Tony clapped his hands together and sat down next to Steve. "Any idea what you'd like to start with?"

"Um. Those pancakes you were making looked good."

"Great." Tony reached for the plate and a bottle of syrup and put both in front of Steve. "Enjoy."

Steve shrugged, made up his pancakes, picked up his fork and dug in.

It didn't take him long at all to finish the plate, even though Tony had given him ten whole pancakes. Steve didn't even seem phased by it.

"What's next?" Tony asked, as he took the empty plate away.

"Those cinnamon things look good."

Tony nodded and got the plate, then put it in front of Steve. It contained several large cinnabuns, all covered in frosting.

"These are amazing," Steve said, as he took a huge bite.

"I got 'em from the Cinnabun store. Glad you like them."

Steve nodded and continued eating, powering through the plate in even a shorter time than he had the pancakes. He reached for a large glass of milk and chugged it before speaking again.

"I guess I'll switch it up. Is that a tray of roast beef?"

"Yup. Here you go," Tony placed the tray in front of him. "Just let me know when you start to feel full. For the experiment."

"Okay."

Steve finished up the tray in record speed. Tony was impressed.

"Wow. You're like a machine."

"I always have to eat a lot," Steve answered. "I'm kinda used to it."

"Right. So, what's next?" Tony moved the tray over.

"I'm kinda thirsty again."

"We've got more milk, water, orange juice, three two liter bottles of coke, the same of Sprite and two gallons of iced tea."

"Coke works."

Tony brought Steve two of the large bottles of soda and watched as Steve managed to drink one down entirely. He wasn't entirely surprised though. Not considering how quickly he'd just seen Steve eat.

"Alright," Steve put down the empty bottle. He wasn't hungry but he wasn't full, either. "Let's try the salad."

Tony quickly put the massive bowl in front of him.

"It's got Ceasar dressing. I remembered that you liked that. Hope it's okay," Tony mentioned.

"Sure."

It took Steve a little longer to get through the salad just because of how much there was to it. The thing had been pre-made to feed a party of twenty people.

"Is it good?" Tony asked, after watching Steve eat for several minutes.

"Yeah, it's good," Steve replied, in between bites.

When Steve finally finished, Tony did his best not to stare at him. He was astonished by how much Steve could eat and not even be phased by it.

"How are you feeling?" Tony was sure that by now he himself would have been either dead or in a food coma.

Steve patted his stomach gently.

"Pretty good. Starting to get there."

"Alright. What next?"

Steve looked everything over, trying to decide. When he couldn't he gave Tony the option of choosing.

"I guess, have the pizza before it gets too cold."

"Okay."

Tony brought the three pizza boxes over and set them down in front of Steve.

"One's extra cheese, one's pepperoni and one's everything."

Steve didn't reply, instead he opened up the first box and pulled out two slices.

The soldier managed to eat all three pies slightly faster than he had eaten the salad. By the end of it, Tony noticed that Steve's stomach was starting to round out, but only a little bit.

"Okay...I'm pretty full now," Steve said, pushing the boxes away.

Tony was torn between letting Steve off or trying to get him to eat more. He didn't want to make Steve too uncomfortable but… But Steve's body would take care of it quickly and it seemed like a massive waste to not try to finish up all that food.

"For the experiment to be a success you should try to finish more of this," Tony motioned at the rest of the food.

"Really?" Steve seemed confused.

"Well, yeah. Obviously I can't calculate what foods would best suit your needs until you try everything."

"How does that make sense?"

Tony glared at him.

"It's _Science_, Steve. Don't you think that I know Science?"

"I just don't understand. Ah, whatever," Steve gave up. It wasn't worth starting an argument over especially since Tony had already gone through the trouble of preparing all the food. "What's next?"

"Well, there's this," Tony said, walking over to the other end of the table. There was a large tray of baked ziti. He picked it up. "I actually made this."

"Aw, you didn't have to do that," Steve motioned for him to bring the food over. "The pancakes were enough."

"I wanted to. Hopefully it'll taste okay."

Steve unwrapped the tray and took a large bite of the pasta.

"This is really good! I didn't know you could cook like this!"

"It was a pretty basic recipe," Tony said, "But I'm glad you like it."

00

Half an hour later and the entire tray was gone. All six pounds of it. Steve was really feeling full now. His stomach was pushing out at least four or five inches from where it normally was. He couldn't even see the drawstring on his pajama pants.

"I think I'm done…" Steve said, resting a hand on his belly. Having never had a belly before, this in itself seemed strange to him.

Tony frowned and pushed Steve's hand away, replacing it with his own. He slowly began to rub Steve's stomach in a circular motion, making the blonde moan.

While Tony mostly focused on making Steve feel better, he occasionally slid his hand further south and under Steve's pj's. Steve groaned every time Tony touched his cock.

The whole sensation was weird. Even though his stomach hurt, he felt aroused by the heaviness of it. It was like a pleasurable pain. Never in his life had he experienced anything like it before. Not only that, Tony seemed to be very attracted to him in this state. He had been able to tell by the look of excitement and lust in Tony's eyes.

Part of him wanted to see how far he could go, how much he could eat. There was still a lot of food left and his stomach didn't hurt _that_ badly. He focused in on a dessert on the side of the table.

Tony, of course, noticed this immediately. He took a break from touching Steve to retrieve it.

"What is it?" Steve looked the dessert over. It looked like some type of cheesecake but it was covered in chocolate and cherries.

"Chocolate cherry cheesecake. That's powdered sugar," Tony pointed to some white speckles.

"Hmm."

Tony picked up Steve's fork and broke off a large piece, then held it up to his lover's mouth. Steve opened up readily.

"Mmm," Steve moaned. The cake and chocolate were both rich. Steve had never eaten anything quite like it.

Encouraged, Tony continued to feed Steve, stopping occasionally to rub Steve's stomach or nibble on his earlobe and neck.

By the time the cake was halfway gone, Steve was having a harder time breathing. His lungs could only expand so much with his stomach pressing up as it was.

Tony, meanwhile, had his hand on Steve's stomach once again. It was hard, filled entirely and jutted out onto Steve's lap. It was a massive change from his normal perfectly sculpted physique and Tony was extremely turned on. Then he noticed that Steve was too. His cock was getting hard.

"You like that?" Tony whispered, nipping at Steve's ear once again. "You like eating so much that your belly's hanging out over your lap?" Right then, Tony reached down and took hold of Steve's dick. "It seems like you love it."

"Christ…" Steve mumbled, "It's so bad but so good…"

Tony kneeled down at Steve's knees and slowly removed his pj bottoms. "Let me make it awesome."

Any doubts that Steve had about his feelings towards the experience were gone when he felt Tony's mouth. The billionaire kept one hand on the side of Steve's stomach, rubbing him as he sucked the blonde off.

It didn't take long for Steve to come, and Tony swallowed it down when he did.

Tony got up to find that Steve's eyes were still closed. He had moved his own hands back to his stomach again, though one soon fell back to his cock where he touched himself briefly.

"Sooo… Did you enjoy that?" Tony asked, once Steve began to recover.

"Yes! I mean - I did, but-" Then Steve began to blush as it occurred to him what had just happened. "But, this is… It's _weird_."

"So?"

Steve kicked around under the table, trying to find his pj bottoms. He didn't feel much like getting up and looking for them but he at least wanted to cover himself. He found it somewhat funny that now, after all he had just participated in, he was feeling modest.

Pitying him, Tony picked them up off the ground and placed them on Steve's lap.

Now that he was covered, Steve seemed to be able to think a little straighter.

"You did all of this because you're turned on by it," Steve said, though there wasn't any hint of anger in his voice.

"Well, kind of but -"

Steve cut him off.

"No, it's okay. You don't have to explain. It was good. I liked it. And I probably would've never done it if you'd just told me outright."

"That's good then," Tony grinned. "Maybe we can do it again sometime."

"It's a definite possibility. For now, though, I think I need to lie down."

"Of course."

Tony held out his hands to help Steve up, then led the blonde off to bed.


End file.
